1. Field
The present disclosure relates generally to space structures and, in particular, to deploying space structures. Still more particularly, the present disclosure is related to a method and apparatus for deploying a space structure, such as a satellite.
2. Background
Launch vehicles may be used to carry payloads, people, or both from the earth into outer space. For example, a launch vehicle may carry a payload such as a satellite into outer space. Once the launch vehicle has reached a desired distance from the earth for deployment of the satellite, the satellite is separated from the launch vehicle through actuation of one or more deployment mechanisms.
Depending on the conditions and systems used during deployment, the satellite may tumble after separation from the launch vehicle. For example, some deployment systems for satellites use explosive bolts or multiple pusher springs to separate the satellite from the launch vehicle. These types of deployment systems release the satellite from multiple points. The potential for uneven force distribution applied to separate the satellite from the launch vehicle from these different points may be such that the satellite tumbles.
Some satellites may include a propulsion system to reduce or stop tumbling, as well as change the orientation of the satellite, or perform other maneuvers. Smaller satellites, however, may not include these types of systems to reduce size, weight, or both in the satellite. Smaller satellites that have limited or no attitude control range from Microsatellite class down to Femtosatellite class. The microsatellite class has a mass from 10 kg to 100 kg, and the Femtosatellite class has a mass from 0.001 kg to 0.01 kg.
For example, a cubesat is a type of miniaturized satellite. A cubesat has a volume of one liter and a mass that is no more than 1.33 kilograms. The dimensions of a 1 U cubesat is 10 cm×10 cm×10 cm. A 3 U cubesat is 30 cm×10 cm×10 cm.
A cubesat typically carries one or two scientific instruments. A cubesat, however, typically does not include a propulsion system. As a result, tumbling that may occur from deployment may exceed the torque authority of other attitude control actuators, like reaction wheels, and may therefore result in tumble rates that cannot be effectively reduced or eliminated by the cubesat subsystems. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.